The Pentagon’s decision to try six Guantanamo detainees on charges of planning the September 11, 2001, terrorist attacks is prompting objections from some victims’ family members and politicians who say the trial should take place in New York rather than in a small courtroom with limited public seating at the naval station at Guantanamo Bay, Cuba.

“Where it happens is where it’s going to happen and we’re not going to get a say,” said a retired deputy chief with the New York fire department, James Riches, whose son, also a firefighter by the same name, died in the North Tower of the World Trade Center. “But these people should be brought to New York where the crime was committed and where the families could go and see the trial and see them face justice.”

Rep. Anthony Weiner, a Democrat who represents parts of Brooklyn and Queens, said in a statement that “if holding this trial in the city eases the heartache of a single person, then we should do it.”

Other relatives of those who died in the terrorist attacks say they are not concerned with the venue.

“If these people are indeed guilty as charged, I’d like them to receive the same death sentence that our children received,” Sally Regenhard, the mother of a firefighter who died in the attacks, Christian Regenhard, said. “I’m more interested in that than in the minutiae of where it’s going to be held.”

Military prosecutors are bringing conspiracy and murder charges and seeking the death penalty against six Guantanamo detainees, including Khalid Sheikh Mohammed, the alleged mastermind behind the attack. The trial may not occur for years as the defense and prosecutors argue over what rules will govern the trial. The courtroom in Guantanamo where the Pentagon plans to hold the trial has a gallery with a seating capacity of 40, a Pentagon spokesman, Commander Jeffrey Gordon, said.

The most recent trial by a military commission against an enemy combatant occurred at the Justice Department’s main building in Washington in 1942.

“There’s no legal barrier to holding a trial on the mainland,” a professor at Georgetown Law, Neal Katyal, who won a case on behalf of a Guantanamo detainee before the U.S. Supreme Court, said. “It’s just that the administration gambled on this risky Guantanamo scheme six years ago and now with a few months left it is trying to offer one last ‘Hail Mary’ to that system.”

Mr. Katyal said there “were no established rules” or precedent for how a commission would respond should one of the six detainees argue that the military commission should occur on the mainland.

“Why does it have to be in Guantanamo?” an Army reserves officer who served on the military board that reviews the detention of Guantanamo inmates, Stephen Abraham, said. “I don’t think anybody could offer a particularly cogent reason other than what are the professed security concerns.”

Lieutenant Colonel Abraham, who has publicly criticized aspects of Guantanamo proceedings in a court affidavit and interviews, said, “It could be the best trial ever conducted, but if it was conducted behind closed doors there could be no person absent his own innate trust in the government who could have any confidence in the result.”

The trial of Zacarias Moussoaui, the only person so far tried by the United States in connection with the attacks, was shown on television in federal court in Manhattan so that family members of victims could follow the proceedings. That trial occurred in a federal courtroom in Alexandria, Va., and occurred within the civilian criminal justice system.

Commander Gordon, the Pentagon spokesman, said video might also be available from the trial of the six at Guantanamo.

In an e-mail, Commander Gordon wrote that there was no possibility the military commission will occur in New York or near the nation’s capital, where the Pentagon, in Alexandria, Va., was also attacked on September 11, 2001.

Rep. Vito Fossella, a Republican who represents Staten Island and part of Brooklyn, said that the trial ought to be held in Guantanamo because “the overarching goal is to ensure that this doesn’t become a spectacle and that justice is served.”

He said: “In a perfect world the trial should occur at the scene of the crime, which would afford family members of victims an opportunity to be present.”